KR102093953B1 - Method for helping determine the vision parameters of a subject - Google Patents

Abstract

The present invention relates to a method of helping to determine a vision parameter of a subject 100, the method comprising the following steps,-two images of the face of the subject from two different angles by the camera 10 Step 120 of photographing the fields I1 and I2, and the subject S is in a natural distant vision posture,-the inclination of the camera 10 relative to the ground when images are taken Determining (inclination) (130), and-Deducing (140) the slope and cap angle value (cap angle value) of the face of the subject S therefrom (140), wherein the camera comprises When the images I1 and I2 are photographed (step 120), they are disposed outside the center and foveal area of the subject.

Description

How to help determine the subject's vision parameters {METHOD FOR HELPING DETERMINE THE VISION PARAMETERS OF A SUBJECT}

The present invention relates to the analysis of the general posture of the subject's face and to the measurements performed by the operator, usually an optician, which operator must wear and is also mounted on the frames Acquisition of data necessary to determine the general composition of the implantation of corrective lenses for the subjects' eyes for personalization and optimization of the optical properties of the corrective lenses or ophthalmic lenses do.

Numerous systems are already known that aim to optimize the position of lenses in a subject's frame relative to the pupils of the eyes and the relative position of the frame. To this end, fixed or animated images of the face wearing the frame are photographed with a camera, and detection of the position of the frame as well as detection of the position of the eyes is performed.

In particular, document FR 2 860 887, filed in the name of the applicant, based on a series of animated images of the subject's face during movement in front of a fixed camera, provides an optimal definition of the relative position of the eyes and frame. Disclosed is a system in which a reference image in which the face is optimally focused on the camera is determined to have.

At the same time, manufacturers of ophthalmic lenses today attempt to optimize the design of these lenses, especially with the technology of so-called progressive lenses, by examining the subject's behavior when the subject's glance moves. . For example, document FR 2 892 529 filed in the name of the applicant discloses a system, wherein the system

- camera,

-A screen for displaying images taken by the camera,

-An accessory that can be fixedly worn on the subject's face and carries a plurality of visual markers,

Means for forming a visual target (s) capable of covering at least two determined positions I1, I2 with respect to the camera,

-Image analysis means capable of analyzing the position of the visual markers in the images taken by the camera. The means of image analysis then deduces the cap angle value in the space of the position and the accessory and therefore the subject observes different areas of the means forming the visual target (s). When deducing, the subject's face's angle of cap angle is inferred, and in particular, information about the relative importance of the movement of the eyes as well as the relative importance of the movement of the face during the movement of the vision from one target to another do.

Typically, the accessory comprises means for conforming to the accessory illustrated in FIG. 2 and forming a specially selected geometric indicator to emphasize the orientation of the frame. It may consist of a rectilinear support with a series of visual markers positioned upwardly on the top surface of the frame and / or along the branches of the frames.

The system then enables precise measurement of parameters such as the position of the pupils, their spacing, etc., because the subject's gaze direction (thanks to visual targets) as well as the positioning of the subject and visual markers This is because the measurement system itself is spatially known and measured.

In order for the measurements to be accurate, the subject's face must also be in a reference pose and watched in a position suitable for making measurements using the system.

The reference pose of the system of interest to the present invention is a pose of distant vision, where the subject remains in a natural position and looks at a point in an infinite straight line in front of him in a horizontal plane (glance). . As a variant, the reference pose may correspond to a close vision posture, such as a reading pose, and the close vision pose is about 30 cm from the subject's eyes and is about 30 cm compared to the horizontal plane. It is a position that lowers one's gaze as much as °.

The subject's pose can be described (eg, in a non-limiting manner) by two angles to a known gaze direction.

The first angle corresponds to the cap angle value of the face, ie the oriented angle reflecting the fact that the subject tends to turn the face more or less to the left or right when looking at the object positioned directly in front of him ).

The second angle corresponds to the vertical inclination of the face, ie the oriented angle reflecting the fact that the subject tends to raise or lower the face more or less when looking at the object positioned directly in front of him. For a given frame, this second angle can be a measure of the pantoscopic angle, ie a measure of the inclination of the mean plane of the corrective lens relative to the vertical.

To determine the distance between the pupils of the subject (one of the parameters for the manufacture of orthodontic devices), an optician typically uses a pupillometer. In this case, the cap angle value is arbitrarily assumed to be zero (zero) because the pupilmetry system is leaning against the subject's front. Nevertheless, the device has a wide viewing angle that must be measured individually, or, if applicable, the manner in which the subject holds his or her head to the side (the subject's tendency to look slightly to the right or left from the subject's reference position). Don't let the facts take into account.

Therefore, this approach does not guarantee that the position taken by the subject accurately corresponds to his natural position. However, this natural position is very important because this natural position determines how the subject will project his gaze on the lenses of the glasses in the most comfortable position. Therefore, a bad pose leads to poor measurements of the centering of the lenses. Therefore, it is most important to select an image with a correct pose for the calculation of the projection of the gaze through the lenses of the spectacles and thus to evaluate the quality of the subject's position during measurement.

Moreover, all of these systems and procedures described above cannot cause the subject to look at a horizontally straight distance without having any visual hindranc, and the viewing devices are subject to the subject when the subject is in remote vision. It is located in the visual field of. In fact, in order to avoid errors of perspective, the image capturing device should be as close as possible to the optical axis X of the subject's gaze, thus positioning the device very far from the subject (store) It is essential to simulate a target point at a greater distance from the subject than using a camera with a large amount of space and powerful zoom). Therefore, visual targets often interfere with the user. For example, the subject's reflection in the mirror makes it possible to double the distance between the subject and the visual target, but the subject is nearsighted or the mirror is sufficiently immersive (with respect to the size of the mirror or the quality of the reflection of the mirror). If not immersive, this may prove difficult to focus on the exact spot on the subject's face. Therefore, the subject may have to adopt his natural long-range vision pose with difficulty.

Additionally, these systems are spatially limited by the space available for installation of the measurement system, so that the visual targets are generally kept close to the subject, much more so that the subject focuses his gaze on the visual targets. It gives more restrictions. Finally, these systems are bulky and require minimal space to approximate a far vision.

Document DE 10 2010 015795 describes a device for determining the centering of a subject, comprising a screen, two cameras disposed on each side of the screen and a processing system. The cameras are preferably not visible to the subject, and images are selected on the screen where the subject is selected to take special positions to measure vision parameters. Several parameters are determined including the head-eye coefficient, the center of rotation of the eye in near vision and far vision. Nevertheless, the method described as a device imposes too short a distance on the person wearing it, which limits this person's gaze, and prevents him from being in a natural reference pose and infinitely distant. Don't let you see the place. Moreover, the system described in this document is very complex.

Document EP 1 747 750 describes, in part, a method of establishing the visual behavior of a subject, the method comprising the following steps.

-The step of providing the accessory to the subject.

The step of allowing the subject to sit facing the screen, the subject must be centered on the cameras, which are extended to each side of the screen to obtain a stereoscopic card of the subject's face.

-Requesting the subject to follow the image on the screen, and following the movement of the face.

-Determining the behavior of the subject based on these images.

Here again, the method requires considerable space for the implementation of the method and constrains the subject to fix the target setting at a relatively close distance, which prevents the subject from posing naturally during measurement.

Finally, document FR 2 971 861 describes a method for determining at least one parameter of the wearer's vision, no matter what the ambient light conditions are, in which method the position of a calibration element of the checkerboard type It is identified on the image of the subject's head and this image is used to adjust the luminance in subsequent captured images. To this end, this document proposes a method in which several images are captured using a camera. The contrast between each capture is improved thanks to the correction elements detected on the preceding image. Therefore, this method aims to improve the quality of images captured by the image capturing device. However, it also requires a bulky system and images of the subject are photographed facing or in profile, constraining the subject's gaze a priori during measurement.

Therefore, one object of the present invention is to propose a new measurement method and related system, which new measurement method and related system are more polyvalent than devices known to date without constraining the gaze of the subject. It enables the accurate determination of the parameters of the vision needed to make the vision correction device, which makes it possible at a moderate cost.

Here, the vision parameters specifically mean the parameters included in the following lists: wide viewing angle, measurement of the distances / heights of the valley and convergence of the eyes in this measurement, eyeglass-eye distance, cap angle value , Eye-hair modulus, etc.

To this end, the present invention proposes a method to assist in determining the parameters of the subject's vision, the method comprising the following steps.

-Capturing two images of the subject's face from two different angles by means of a portable image capturing device, the subject being in a natural pose for the far vision.

-Determining the slope of the image capturing device relative to the ground at the time the images were captured.

-Deducing the slope and cap angle values of the subject's face from this.

Here, the image capturing device is set outside the center and zone of the subject at the time the images are captured.

In this way, the image capturing device does not constitute a visual obstruction to the subject's field of view. In fact, this no longer cuts the axis of the subject's line of sight, so focusing on a horizontally distant target and constraining the head's carriage and / or pupil, without being constrained by space or measurement devices. When measuring separations / heights it is possible to limit the errors associated with the convergence of the eyes.

Specific options that do not limit the features of the method are as follows.

* During the capture of images, the subject's field of view in which the image capturing device forms a cone with an apex angle of 5 ° to 30 ° with respect to the subject's visual axis, preferably between 15 ° and 25 ° Is placed outside the zone.

* As can be seen below, one of the images is taken facing the subject.

* One of the images is taken from the side.

Thus, this arrangement of the image capturing device makes it possible to avoid constraining the subject's gaze and position by not blocking the subject's field of vision.

* At least one of the pupils of the subject or at least one of the corneal reflections is visible on each of the captured images.

* The process additionally includes the step of identifying visual markers in the images, which are formed on an accessory that can be worn in a manner that is secured to the subject's face.

* The image capturing device is a video camera, and the image capturing step includes the following sub-steps.

-Filming a subject's face to obtain a plurality of images of the subject from different angles of view, and

-Selecting at least two images of the subject's face from two different angles among the subjects' images.

The method also includes the step of identifying visual markers in the images, said visual markers being singular points of the subject's face.

* The images are taken simultaneously by two image capturing devices-the image capturing devices are known to each other by a position and a cap angle value.

* At the time of capture of the two images, light is illuminated on the subject's face.

* During the step of capturing the image, a ray of light is projected onto the backing facing the subject, eg a vertical segment.

* The inclination and cap angle values of the subject's face are determined locally by the image capturing device or remotely on an internet server or on a local computer remote from the image capturing device.

* The image capturing device is a digital tablet that includes a video camera.

Thus, the possibility of implementing a help method consistent with the present invention makes it possible to adopt digital tablets, which may be commercial or dedicated, for taking images of the subject and determining the vision parameters of the subject.

Other features, objects and advantages of the present invention will become more apparent upon reading the following detailed description with reference to the accompanying drawings given as non-limiting examples.
1 is a schematic diagram of an embodiment of a system to assist in determining parameters of a subject's vision consistent with the present invention.
2 is an example of an accessory that can be used with a system consistent with the present invention.
3 is an embodiment of an image capturing device that can be used in a system consistent with the present invention.
4A and 4B show examples of image captures consistent with the present invention.
5 is a flow diagram illustrating various steps of an embodiment of a method for assisting in determining vision parameters of a subject consistent with the present invention.

In particular, the system 1 that assists in determining the vision parameters of the subject S consistent with the present invention,

-The face of the subject S-the face of the subject includes visual markers-an image capturing device 10 configured to shoot images of,

An inclinometer integrated with the movement of the image capturing device, and

-Processing means connected to said image capturing device and said inclinometer.

Generally, to determine the vision parameters of a subject, an operator (eg, an optician) photographs at least two images I1, I2 of the subject at different angles by an image capturing device, where the subject captures the image None of I1 or I2 is looking away so as not to disturb the subject.

To this end, the image capturing device does not interfere with the subject's gaze and is positioned away from the subject's visual axis X, preferably with the center of the subject so that the subject S is positioned in a natural pose and looking away without external constraints. It is located outside the area. In fact, it is important not to block the center and zone so as not to interfere with subject S. However, in order to reduce the risks of interference, it may be desirable to provide a larger area than the center and area. Thus, according to one embodiment, the image capturing device 10 has a vertex angle of 5 ° to 30 ° with respect to the visual axis X of each eye of the subject S, preferably for each of the captured images I1 and I2, It is positioned outside the field of view of subject S forming a cone having a vertex angle between 15 ° and 25 ° (the cone's vertex is disposed on the visual axis at the subject's face).

In fact, the farther away the image capturing device 10 is from the visual axis X of the subject S, the less subject will be obstructed by the presence of the image capturing device, and this limitation is at least one of the pupils of the subject S ( Or, at least, it will be understood that this is the ability to accurately discern corneal reflection.

Then, no visual target is imposed on the subject S, so that the subject can adopt his natural, far vision pose. However, it is possible, for example, for the operator to present this target to the subject S so that the subject S sees directly in front of him. However, this target is not part of the system 1 and its position is not defined for the image capturing device 10.

The inclination angles of the images and the image capturing device 10 are analyzed by processing means inferring the subject's vision parameters from them.

image Capturing device (10)

The image capturing device 10 may be a video camera, a photographic device, or the like. The images captured by the image capturing device 10 can be digital images, in particular, to be processed directly by processing means.

The image capturing device 10 preferably has a wide-angle lens so that it can take a complete image of the subject's face at a short distance between 10 cm and 1 meter. The resolution of the image capturing device 10 depends on its focal length, distance to person, etc., and can generally identify visual markers 45 such as color markers or single points on the face. It should be enough. For example, the resolution of the image capturing device 10 should be sufficient for the image of the eyes to include at least one pixel every 0.3 mm.

The system 1 also includes an inclinometer 20 integrated with the movement of the image capturing device 10 designed to determine the inclination of the image capturing device 10 relative to the horizontal plane. Preferably, the inclinometer 20 is integrated with the image capturing device 10. It can be, for example, an accelerometer coupled to an acceleration signal processing circuit. The accelerometer can also be coupled to an electronic gyroscope to improve the reliability of the inclinometer.

Optionally, the system 1 can also include lighting means 12 for the subject's face, in particular to measure the corneal reflection of the subject, said lighting means 10 being an image capturing device 10 ).

Moreover, the image capturing device 10 is movable and portable by an operator to facilitate its use. It may additionally include a screen 14, which may allow the operator to visualize images captured by the image capturing device 10.

In the embodiment shown in the figures, the image capturing device 10 comprises, for example, an accelerometer 20 as well as a video camera 11 capable of taking images on its rear face 16 Is a digital tablet. The tablet 10 may additionally include a screen 14 on its front side, and the screen may visualize images captured by the camera 11 in real time. It is made of, for example, iPad® type, Calico Tab® type, commercial tablets for iphone, especially tablets or even smartphones made for application to the determination of the subject's vision parameters and comprising an image capturing device and an adapted inclinometer. You can.

Advantageously, the camera 11 is then still held outside the center and area of the subject, preferably supporting the capture of the subject's images while still not perturbing the subject's natural long-range vision pose, preferably the subject Positioning, for example, close to one of its ends, such that it remains outside the field of view forming a cone with a vertex angle of 5 ° to 30 ° with respect to the time axis X of S, more preferably even between 15 ° and 25 ° Can be offset relative to the geometric center of the tablet 10.

Optionally, the flash of the tablet 10 can be used as the lighting means 12 during image capture. However, the tablet 10 may be provided with a lighting means 12 attached to the tablet, which is separate from the flash, in particular with respect to the back of the tablet, so as to illuminate the face of the subject S during image capture.

Moreover, the image capturing device 10 also includes a projector 18 designed to project a visual target against the back facing the subject S. For example, the projector 18 can be a low power laser designed to project a luminous ray on a wall.

According to another embodiment, the image capturing device 10 may be formed of a screen 12, wherein at least the arm 16 equipped with the camera 11 is detachable or permanent. Is fixed by. The arm 16 may articulate about an axis that is globally perpendicular to the edge of the screen on one of the edges of the screen 14 (eg, the upper edge). The arm 16 can be pivoted by an angle greater than 90 °, eg, about 120 °, so as not to interfere with subject S during image capture. The arm can also rotate (locally or over the entire length of the arm) while working with the camera 11, making it easier to frame the subject's face. For example, the arm 16 can turn around its axis at an angle of about 200 °.

By way of example, the arm 16 measures about 30 centimeters and can include two cameras 11 aligned along the arm and separated by about 10 centimeters. This embodiment can then cause two pictures I1, I2 of the face of the subject S to be taken simultaneously at two different viewing angles.

In this embodiment, the arm 16 mounted on the camera (s) 11 can then be attached to the commercial tablet 10. The inclinometer 20 can then be secured (or integrated with it) on the tablet 10 or can be secured on the arm 16 itself. Moreover, the attachment of the arm 16 can be performed on the screen 10 directly or by adapter 14 (especially if the screen is a commercial digital tablet).

Visual Markers

The visual markers may be sole points on the face of the subject S or visual markers carried by the accessory 40 worn on the subject's face.

The accessory 40 illustrated in FIG. 2 may in particular conform to the accessories described in documents FR 2 860 887 or FR 2 892 529. This accessory 40 made of, for example, transparent plastic comprises a horizontally elongated body 42 having two side branches 43 which are also horizontal, the side branches being rearward relative to the body. It extends substantially at right angles. Body 42 carries two small clamps designed to attach along the upper edges of the two lenses (or on the frame) of the glasses worn by subject S along the lower edge of the body, and the branches 43 can also hold the means in an unillustrated manner, said means for holding this means on branches of the frame. In this way, as soon as the subject wears the glasses (corrected or optically neutral or even a bare frame) in a stable position, and as soon as the accessory 40 is not in place, the accessory is well defined for the subject's face Occupied position.

According to one aspect of the invention, the accessory can also correspond to two elastic blades 44 of metal or plastic, the elastic blade extending from the lower edge of the body and its curved shape ( The curved form) is adapted to lean against the lower edge of the lenses of the glasses (or frame). The shape of the blades 44 is also adapted to follow a straight trajectory perpendicular to the body when their free end is deformed such that they are fixed onto the lenses (or frame). In this way, the blades 44 are always fixed in the same position on the lenses (or frame) during the measurements and do not disturb the subject's gaze regardless of what type of frame the subject has.

As illustrated in FIG. 2, accessory 40 includes a certain number of visual markers or criteria 45, here 8 square regions with a well-identified color, such as light green with a well-defined wavelength. Included, two visual markers are fitted to these well-defined spaced positions in one of the branches 43, the other two are placed symmetrically on the other branch 43, and finally the other four The dog is located on the body. More precisely, with respect to these last markers, the body 42 of the accessory 40 includes an upwardly projecting portion 46 and a forwardly projecting portion 47, in the upper region of the portion 46 A marker 45 is found and a marker 45 is present at the free end of the portion 47. At least two markers 45 are left and right near the departure of the branches 46.

As a variant, the visual markers 45 can be geometric shapes such as checkerboards or even markers emitted in the infrared spectrum.

When the visual markers are the sole points of the face, these may be points on the edges of the subject's frame, as well as pupils and / or corneal reflections.

Processing means (30)

The processing means 30, as well as the position of the visual markers in the images I1, I2 taken by the image capturing device 10, to infer the vision parameters of the subject S, as well as the inclinometer 20 at the time of each image capture It is designed to analyze the slope of the device 10 determined by).

To this end, the processing means 30 comprises data from the image capturing device 10 (images I1 and I2 of the face of the subject S) and data from the inclinometer 20 (image capturing device 10 against the ground). Tilt). The results can then be displayed on the screen of the processor, or, if applicable, on the screen 14 of the image capturing device 10.

The processor 30 can be integrated directly into the image capturing device 10. This may be the case, in particular, when the image capturing device 10 is a digital tablet. Then, all calculations are performed locally on the digital tablet 10.

As a variant, the processor 30 may be a local computer separate from the image capturing device 10, but located adjacent to the image capturing device. The image capturing device 10 then data (images and angles) to the computer that performs the calculation, via a network (wireless or wired) 32 that makes it possible to obtain the parameters of the subject S 'vision. To send. Advantageously, the system 1 can then be integrated as a supplement to existing measurement systems, such as those described in the documents cited at the beginning of this application, and thus the existing interfaces ( Benefiting from software, management interfaces, etc.) reduces development costs, the cost of purchasing systems when opticians already have existing systems, and reassures opticians who already understand the equipment.

In this variant embodiment, when the image capturing device 10 is a digital tablet, the screen of the processor is a tablet (such as a Virtual Network Computing (VNC) protocol or a Remote Desktop Protocol (RDP)) by an access system in a remote office. 10) can be displayed on the screen 14, thus allowing the operator to manage all operations directly from his tablet 10.

According to another variant, the processor 30 can be a remote Internet server, and the Internet server can be further dedicated. Then, the inclinations of the images I1, I2 and the measurement device are transmitted (by a wireless or wired network) to a remote server 30, which remote server, in particular, for the image capturing device 10 to display the results If screen 14 is included, the results are sent back directly to image capturing device 10 or the results are sent to a local computer connected to a remote server.

When the visual marker is formed as a single point of the subject's face, the processor 30 makes the measurements necessary to realize the three-dimensional reconstruction of the patient's face and to determine the subject's vision parameters from the reconstruction. Means for.

To this end, triangulation for 3D reconstruction is performed in accordance with the prior art. Then, accessory 40 makes it possible to know at least one known distance between two points.

As a variant, the three-dimensional reconstruction can be performed by any other conventional photogrammetry or stereoscopy method.

In a variant embodiment that implements sole points of the face, the system 1 comprises at least two image capturing devices 10, the spatial positions and directions of which are relative to each other. It is then possible to determine the positions of the sole points of the face and their distances thanks to the reference images taken simultaneously with the two image capturing devices 10 according to the photogrammetry and stereoscopic techniques described above. Do.

Way

Now, a method 100 will be described to assist in determining vision parameters of a subject consistent with the present invention. The method 100 will be illustrated below using a system 1 consisting of a digital tablet 10 comprising a screen, a video camera and an accelerometer 20. However, this is non-limiting, and the method 100 can be implemented with all image capturing devices 10 and inclinometers 20 conforming to those described above.

To achieve these measurements, subject S is first positioned in his natural reference pose and looks away (step 110). To do this, the subject relaxes the mind and body and looks at an infinite point just in front of himself on a horizontal plane. Therefore, this position is free, not constrained, so that the subject does not need to look at the required visual marker or look in the mirror.

The operator then captures at least two images I1, I2 of the subject's face at a short distance, and this capture is accomplished by framing the face such that at least one of the subject's pupils is found in the two images (step 120). . In this way, it is then possible to perform at least measurements on the corresponding eye. Considering the short distance (between 10 centimeters and 1 meter) between the camera 11 and the face of the subject S, images I1 and I2 with good resolution are obtained. An example of the arrangement of the image capturing device 10 and the video camera 11 during the capture of images I1 and I2 for the face of the subject S and for the visual axis of the subject is illustrated in FIGS. 4A and 4B.

When the image capturing device 10 is a video camera, it is possible to take two images I1 and I2 directly from two different viewing angles or to shoot the face of a subject. The photographing is performed in such a way that a plurality of different images of the image of the subject S are photographed at different viewing angles. Then, two images I1 and I2 photographed at different viewing angles and suitable for the method are selected from the plurality of images. For example, by displacing the video camera 10 between the subject's lateral position and the position under the subject's face that does not interfere with the subject's gaze (i.e., staying away from the subject's center and area) It is possible to shoot a face. This selection of images makes it possible to determine the different vision parameters of subject S.

If the visual markers 45 are the sole points of the face, the images I1 and I2 are preferably taken simultaneously by two separate image capturing devices 10, where their position and orientation relative to each other is known have.

Depending on the option, the lighting means 12 can illuminate during the entire image capture step 120 or simply at the time of each image capture. If the visual markers 15 are markers 45 located on the accessory, the lighting means 12 may be positioned on the accessory 40 itself rather than on the tablet 10 to illuminate the pupils of subject S.

If necessary, the operator can use the tablet's screen 14 to help accurately frame the image of subject S.

For example, the operator shoots the image I1 from the front as seen from below, so that the two pupils are visible, so as not to penetrate into the subject S's watch, and thus not interfere with the subject's natural long-range vision pose. Image I2 is taken from the side at an angle less than ° (eg, 3/4 view).

As a variant, the operator can take two images I1, I2 from the sides of the face at different angles from the viewing axis of the subject S, such as 20 ° and 40 °, so as not to interfere with the subject's field of view. These images I1, I2 can be obtained continuously by moving the tablet 10 between two image captures I1, I2, or an arm equipped with two cameras 11 with the tablet 10 spaced apart. When equipped with 16, it can be obtained simultaneously.

During these measurements, images I1 and I2 are then registered by digital tablet 10, and accelerometer 20 determines the tilt of tablet 10 at the time of each image capture (step 130).

Then, the inclination of the images I1, I2 and the tablet 10 determines the position of each of the various visual markers in the two images I1, I2 and from there the vision parameters such as the convergence of the subject S as well as the subject It is sent to the processor 30 to infer (step 140) the natural slope of the face and the natural cap angle value.

The determination of the visual markers can be made automatically by the processor 30 itself or manually by the operator.

The digital tablet 10 is generally tactile, and the operator can visualize and point visual markers directly above the images I1, I2 displayed on the screen 14, in particular. Therefore, it is possible to determine the positions of the irises and pupils by applying the principles of photogrammetry and stereometry. This information is then used by processor 30 to infer the convergence of subject S therefrom.

Optionally, when illumination is illuminated by the illumination means 12 on the subject's face, the processor 30 also converges the subject S from the position of the corneal reflections and irises of the subject using conventional calculation methods. Can decide.

These results are then displayed on the screen 14 of a tablet or a computer positioned nearby.

To improve the measurement of the subject's natural cap angle value, a visual target, preferably a vertical segment, is projected onto a support, such as a wall, by a project 18 fixed to the tablet 10, and the patient at the time of image capture. It is possible to ask to see this target. In this way, the subject places his head in a position corresponding to the zero cap angle value.

The visual target may be a vertical segment that does not interfere with the measurement of the tilt of the subject's face.

Claims (14)

A method (100) to help determine a subject's vision parameters, the method comprising the following steps:
-Capturing (120) two images (I1, I2) of the subject's face from two different angles by the image capturing device (10)-the subject (S) is a natural far vision pose ( natural distant vision posture)-Wow;
-Determining (130) the inclination of the image capturing device 10 with respect to the ground at the time of image capture;
-Deducing (140) the inclination of the face of the subject S and the cap angle value.
The image capturing device is assisted in determining vision parameters of a subject, characterized in that it is positioned outside the center and foveal area of the subject at the time of capture (step 120) of the images I1 and I2. . According to claim 1,
The image capturing device 10 is located outside the area of the field of vision of the subject S during image capture (step 120), the area being the optical axis of the subject S ( A method to help determine the vision parameters of a subject characterized by forming a cone having an apex angle of 5 ° to 30 ° for X). The method according to claim 1 or 2,
One of the images (I2) is to help determine the vision parameters of the subject, characterized in that taken from the front of the subject from below. According to claim 1,
Method of helping to determine the vision parameters of a subject, characterized in that one of the images (I2) is taken from the side. According to claim 1,
At least one of the pupils of the subject S or at least one of corneal reflections is visible on each of the captured images I1, I2. How to help determine vision parameters. According to claim 1,
Visual markers (45) further comprises the step of being identified in the images, the visual markers (45) are formed on the accessory (40) fixedly worn on the face of the subject (S) How to help determine the vision parameters of the subject, characterized in that. According to claim 1,
The image capturing device 10 is a video camera, and capturing the images comprises the following sub-steps:
-Filming the subject's face to obtain a plurality of images at different viewing angles, and
-Selecting at least two images (I1, I2) of the face of the subject (S) at two different angles among the images of the subject to determine vision parameters of the subject How to help. According to claim 1,
The visual markers 45 further include the step of identifying in the images, the visual markers 45 being the singular points of the face of the subject S, the vision parameter of the subject How to help them decide. The method of claim 8,
The images I1 and I2 are simultaneously photographed by two image capturing devices 10, and the position and relative orientation of the image capturing devices is known to determine the vision parameters of the subject, characterized in that it is known. How to help. According to claim 1,
At the moment of capture of the two images (I1, I2), a method of helping to determine the vision parameters of the subject, characterized in that the light is lit (lit) on the face of the subject S. According to claim 1,
During the step consisting of capturing the images I1, I2, the beam of light determines the vision parameters of the subject, characterized in that projected onto a support facing the subject S, such as a vertical segment How to help. According to claim 1,
The subject's face tilt and cap angle values are determined by the image capturing device locally or remotely on a local computer or an Internet server remotely from the image capturing device. To help determine your vision parameters. According to claim 1,
The image capturing device (10) is a digital tablet that includes a video camera (11). According to claim 2,
The image capturing device 10 is located outside the field of view of the subject S during image capture (step 120), the region being 15 ° to 25 ° with respect to the visual axis X of the subject S A method of helping to determine the vision parameters of a subject, characterized by forming a cone having a vertex angle of.

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